Butanol is a high quality fuel and fuel additive. Butanol can be mixed, stored and transported together with gasoline. It has more energy per gallon than ethanol, which translates into better fuel economy for consumers using butanol blends, and has lower vapor pressure than ethanol, which translates into less ground level pollution. Butanol's low vapor pressure makes it an attractive low volatility, oxygenated, blend component for refiners to use in complying with stringent vapor pressure specifications. Butanol can provide the oxygenate benefits of ethanol but without undue evaporative emissions, which are a significant source of air pollution, and at a potentially lower cost. Butanol is also more hydrophobic than ethanol, i.e., it has a higher tendency to repel water, and is more suitable for blending with gasoline. As such, butanol should be a highly desired component of Reformulated Gasoline Blendstock for Oxygenate Blending (RBOB) and California (CARBOB) fuel blendstock. Butanol is also expected to have a reduced life cycle emission of CO2. Butanol blends should have no detrimental effects on modern fuel system elastomers, and corrosion and electrical conductivity are expected to be similar to gasoline.
Butanol can also be blended in concentrations in excess of 20% with diesel fuel. The benefits of addition of oxygenates to diesel fuel include the reduction in soot formation, CO, and unburned hydrocarbon emissions. Importantly, addition of butanol to diesel fuel in concentrations sufficient to realize these benefits retains the flammability rating (flash point) of the diesel fuel without oxygenate. This is a significant benefit to deployment and implementation.
Butanol is also widely used as an industrial chemical. It is used in the production of paints, plasticizers, and pesticides, as an ingredient in contact lens cleansers, cement, and textiles, and also as a flavoring in candy and ice cream. The global market for n-butanol was approximately 1 billion gallons in 2006; the U.S. market was approximately 300 million gallons, and is expected to grow approximately 2% per year.
Butanol is currently made from petroleum. Production costs are high and margins are low, and price trends generally track the price of oil and are heavily influenced by global economic growth.
There is a need for improved methods for production of butanol. In particular, methods for environmentally compatible, cost efficient, and energy efficient production of butanol would be desirable.